Cold start questions?

[roadracemiata]

I have a 92 standard package, 1.6 motor. It has about 50k on the motor. Fresh timing belt, slightly advanced ignition, k and n cone filter, 2" exhaust, no catalytic converter. The engine was installed and tuned by a 12 time NASA spec miata endurance racing champion. When it is cold or the car has not been driven for a while, i get a rough idle almost like its only firing on 3 cylinders. When it warms up to temp it runs like a bat out of hell. I have been told that the older 1.6 cars can be finicky when you play with the timing. It has a stock reccomended gap in the spark plugs. All vaacum hoses and connections are in tact. I do sometimes use this car for boring day to day driving, and if i can fix this problem id like to. Sometimea it even stalls out when you hop in and try to drive immediately. Anyone experience this? Any advice would be appreciated thanks!

[roadracemiata]

ImageUploadedByTapatalk1397361765.694933.jpg

[Left0verCurry]

How did your sparks plugs look when you checked the gap?
When were your coil packs last replaced?
Check your idle speed control valve (ISCV), and clean if dirty.

[roadracemiata]

Where is the iscv? Plugs are brand new, and the coils were replaced when the motor was swapped

[— kung fu jesus —]

Plug wires too?

The ISCV on a 1.6 is screwed to the bottom of the throttle body. There are three hoses coming out of it, including the funky, upside down 'J' shaped hose on the passenger side of the throttle body.

After you locate it, try unplugging the electrical connection for it and see if it helps, your idle will be high.

If you want to remove it for cleaning, you have to remove the throttle body. Do not use harsh chemicals or you will destroy it. The three screws that attach the ISCV are soft so use the proper sized Phillips screwdriver and a small pair of vice grips together. Underneath, there is a gland gasket that may be stretched out and ruined if you remove it. It can be delicate.

I would clean the ISCV and the throttle body separately off the car, reassemble and go from there. While you are at it, check your intake tract for cracks, splits and leaks. Make sure all the connections are snug, too.

ISCVs are around $400 new, so if you come across one in a junkyard, grab it for a spare and recondition it.

[roadracemiata]

Good to know man thanks. Ill give it a good once over